Are you getting a low disk space warning in Windows? Or maybe you have been prompted to delete a previous version of Windows to gain some disk space? If so, here's how to quickly free up space on your drive.

We have all been there. You are working along, and suddenly, a little dialog box pops out and tells you that you are low on disk space. It used to happen a whole lot more years ago when drives were smaller. But it is scary when it does pop up.

Disk Cleanup

Now one way to quickly free up some disk space is to use the built-in Disk Cleanup utility. If you click on the Low Disk Space warning, it brings up Disk Cleanup with default settings.

The default settings for Disk Cleanup are pretty good and will do the job. But there are more advanced settings that can clean up even more files; you have to know how to get to them. You can also run Disk Cleanup as a Scheduled Task. Check out the links below.

Clean up Windows 11 with Disk Cleanup

Clean up Windows 10 with Disk Cleanup

Manually delete temporary files

If you want to delete the temporary files/folders quickly on your computer, here's a quick, down-and-dirty way to do it. All you have to do is bring up a Run dialog box.

How to open a Run dialog box

• On the keyboard, press the Windows logo key + R
  or
• Right-click on the Start button and then select Run

In the Run dialog box that appears, cut and paste or type either

%temp%

User temp folder location

%systemroot%\temp

System temp folder location

and then select OK. If you get a prompt telling you that you do not currently have permission to access the folder, click on the Continue button. File Explorer will open and display the contents of that folder.

Now highlight one of the files and then press the CTRL + A keys simultaneously to select all of the files/folders. Right-click on them and select Delete. If you get a prompt about permanently deleting the files, left-click on Yes. If you get a prompt telling you that a file is still in use, make sure the Do this for all current items checkbox is selected and then left-click on Skip.

Turn off hibernation

If you still need to free up some space, you can turn off hibernation and delete the hilberfil.sys file. That should give you a few more gigabytes of free space. You will need an administrative command prompt to run these.

How to open a Command Prompt with Administrator privileges in Windows 11

How to open a Command Prompt with Administrator privileges in Windows 10

Once you have an administrative command prompt open, just cut and paste or type the following into it:

powercfg.exe /hibernate off

Turn off hibernation

powercfg.exe /hibernate on

Turn on hibernation

Graphic Visualization Tools

Nothing can beat an excellent visual treemap when it comes to finding large files or folders. Instead of the usual file/folder data like in File Explorer, a graphic visualization tool shows file/folder information using blocks. The larger the square, the bigger the file/folder.

Years ago, I started using a graphic visualization tool when I had a client that all of the desktops began running out of disk space. Using a visualization tool, I found that the network-deployed anti-virus clients were downloading new virus definitions, but they were not deleting previous versions.

Now there are a couple of different graphic visualization tools out there. I first started using SpaceMonger but have since moved over to SpaceSniffer. It does not require any installation (unzip and go) and is entirely free (but donations are recommended).

Now, right out of the box, SpaceSniffer can be a bit overwhelming with all of the information it provides. But with a couple of changes to the configuration, SpaceSniffer can open up just the way you like.

Now be careful not to go crazy and start deleting folders/files in the Windows folder. I know that it is one of the largest folders on the C: drive, but resist the urge to delete anything inside of the Windows folder. I would focus on the size of the user(s) folders/files. For more information on SpaceSniffer follow the link below.

See what your drive contains with Space Sniffer

If you're a hardcore computer user like me, your system runs 24/7 with no screen or power saver options (I turn off the monitors when not in use). I like to walk into my office and have it ready to go. So when I noticed that my version of Windows still had the Hiberfil.sys file and I do not use hibernation, it was time to remove this file and regain that drive space back (in my case, 16 GB).

The Hiberfil.sys is a hidden system file located in the drive's root folder where Windows is installed. The Windows Kernel Power Manager creates this file when you install Windows. The computer uses the Hiberfil.sys file to store a copy of the system memory on the drive when hibernation is turned on.

The size of the Hiberfil.sys file is approximately equal to how much Random Access Memory (RAM) is installed on the computer. The computer cannot go into hibernation if this file is not present. And even if you have disabled hibernation, your computer can still go to sleep. Here is the difference between sleep and hibernation:

• Sleep: Windows can turn off the screen(s) and drive(s) while continuing to run in memory. A tap on the keyboard or moving the mouse will turn the screen(s) and drive(s) back on.
• Hibernation: Windows takes the active memory, writes it to the Hiberfil.sys, and then turns the computer off. Pressing the power button will start Windows back up, where it loads the Hiberfil.sys file.

How to turn on or off hibernation in Windows

To disable hibernation, you must open a Command Prompt with Administrator privileges. Since this article covers multiple versions of Windows, click on the link below that matches your version of Windows for how to open an Admin Command Prompt. All links open in a new window.

How to open a Command Prompt with Administrator privileges in Windows 11

How to open a Command Prompt with Administrator privileges in Windows 10

How to open a Command Prompt with Administrator privileges in Windows 8

How to open a Command Prompt with Administrator privileges in Windows Vista and Windows 7

To delete the Hiberfil.sys file and make hibernation unavailable, follow these steps:

1. Open a Command Prompt with Administrator privileges (see instructions above)
2. At the Command Prompt, type powercfg.exe /hibernate off and press ENTER.
   
3. Type exit and then press ENTER to close the Command Prompt window.

To recreate the Hiberfil.sys file and make hibernation available, follow these steps:

1. Open a Command Prompt with Administrator privileges (see instructions above)
   
2. At the Command Prompt, type powercfg.exe /hibernate on and press ENTER.
3. Type exit and then press ENTER to close the Command Prompt window.